1. Field of the Invention
This invention relates to the production of electro-acoustic transducers, such as, electrostatic or condenser microphones or speakers of the type used in headphones of audio equipment, and more particularly is directed to improvements in the production of the diaphragm assemblies for such electro-acoustic transducers.
2. Description of the Prior Art
In existing electro-acoustic transducers of the described type, it is known to provide a diaphragm constituted by a thin film of a high polymer electric insulating resin which is capable of the long retention of an electric charge applied thereto, for example, by irradiation with electrons or a corona discharge, so as to form an electret. The electret diaphragm is then mounted in spaced parallel relation to either a single fixed electrode or between a pair of fixed electrodes to form an electro-acoustic transducer. When the electret diaphragm is associated with only a single fixed electrode, a conductive metal layer of gold, aluminum or the like is vapor deposited on the surface of the diaphragm which faces away from the fixed electrode. In either case, that is, whether the electro-acoustic transducer has a single fixed electrode or a pair of fixed electrodes, the electret diaphragm is supported, at its periphery, by one or more metal frames which maintain the diaphragm in spaced relation to the fixed electrode or electrodes. Since the high polymer film employed for the electret diaphragm is very thin, for example, has a thickness of only approximately 2 to 60 microns, it is desirable that such film be securely attached, while under tension, to the associated metal frame or frames so that the latter will support the diaphragm and provide a convenient means by which the diaphragm can be handled when assembling the electro-acoustic transducer.
In the prior art, it has been the usual practice to adhesively secure the diaphragm to its supporting frame or frames by applying a coating or coatings of epoxy resin to the diaphragm and then pressing the frame or frames against the epoxy resin coated surface or surfaces of the diaphragm while the latter is tensioned until the epoxy resin sets or hardens. However, the foregoing process for securing the metal frame or frames to the diaphragm is relatively complicated and time consuming.